"Print Screen" from MS-DOS Application May Print Twice

When you use the "Print Screen" (PrintScrn) key to print the contents of an MS-DOS application running on Windows NT 4.0, two copies of the screen contents may appear in the printer output.

This problem typically occurs only on very fast computers, such as an Intel- based computer with a P200 processor, and only if the MS-DOS application Program Information File (PIF) setters are set to pass the print-screen event to the MS-DOS application.

The Windows NT Virtual DOS Machine (Ntvdm.exe) incorrectly initiates another print-screen event during the key-up event when you release the PrintScrn key, even though it should only initiate a print-screen event during the key-down event.

While Windows NT processes a print-screen event, it cannot accept and queue up another print-screen event for later processing. Therefore, on slower computers the second print-screen event caused by the key-up event is initiated but never accepted by Windows NT because Windows NT is still busy processing the first print-screen event. However, on faster computers, Windows NT may have completed the first print-screen event by the time the key-up event initiates another print-screen event, resulting in two copies of the screen in the output.

The Virtual DOS Machine (Ntvdm.exe) has been modified to pass a single print-screen event when the PrintScrn key is pressed.

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.